snmpoctetstring.java

基于snmp/mib的网络数据获取系统设计与实现

/*
 * SNMP Package
 *
 * Copyright (C) 2004, Jonathan Sevy <[e-mail]>
 *
 * This is free software. Redistribution and use in source and binary forms, with
 * or without modification, are permitted provided that the following conditions
 * are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice, this
 *     list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation 
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products 
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */


package snmp;

import java.io.*;


/**
*    Class representing a general string of octets.
*/

public class SNMPOctetString extends SNMPObject
{
    protected byte[] data;
    protected byte tag = SNMPBERCodec.SNMPOCTETSTRING;
        
    
    /**
    *    Create a zero-length octet string.
    */
    
    public SNMPOctetString()
    {
        data = new byte[0];
    }
    
    
    /**
    *    Create an octet string from the bytes of the supplied String.
    */
    
    public SNMPOctetString(String stringData)
    {
        this.data = stringData.getBytes();
    }
    
    
    
    
    /**
    *    Create an octet string from the supplied byte array. The array may be either
    *    user-supplied, or part of a retrieved BER encoding. Note that the BER encoding
    *    of the data of an octet string is just the raw bytes.
    */
    
    public SNMPOctetString(byte[] enc)
    {
        extractFromBEREncoding(enc);
    }
    
    
    
    
    /**
    *    Return the array of raw bytes.
    */
    
    public Object getValue()
    {
        return data;
    }
    
    
    
    
    /** 
    *    Used to set the value from a byte array.
    *     @throws SNMPBadValueException Indicates an incorrect object type supplied.
    */
    
    public void setValue(Object data)
        throws SNMPBadValueException
    {
        if (data instanceof byte[])
            this.data = (byte[])data;
        else if (data instanceof String)
            this.data = ((String)data).getBytes();
        else
            throw new SNMPBadValueException(" Octet String: bad object supplied to set value ");
    }
    
    
    
    
    
    /** 
    *    Returns the BER encoding for the octet string. Note the the "value" part of the
    *    BER type,length,value triple is just the sequence of raw bytes.
    */
    
    protected byte[] getBEREncoding()
    {
        
        ByteArrayOutputStream outBytes = new ByteArrayOutputStream();
        
        // calculate encoding for length of data
        byte[] len = SNMPBERCodec.encodeLength(data.length);
        
        // encode T,L,V info
        outBytes.write(tag);
        outBytes.write(len, 0, len.length);
        outBytes.write(data, 0, data.length);
    
        return outBytes.toByteArray();
    }
    
    
    
    
    protected void extractFromBEREncoding(byte[] enc)
    {
        data = new byte[enc.length];
        
        // copy data
        for (int i = 0; i < enc.length; i++)
        {
            data[i] = enc[i];
        }
    }
    
    
    
    /**
    *   Checks the embedded arrays for equality.
    */
    
    public boolean equals(Object other)
    {
        // false if other is null
        if (other == null)
        {
            return false;
        }
        
        // check first to see that they're both of the same class
        if (!this.getClass().equals(other.getClass()))
        {
            return false;
        }
        
        SNMPOctetString otherSNMPObject = (SNMPOctetString)other; 
         
        // see if their embedded arrays are equal
        if (java.util.Arrays.equals((byte[])this.getValue(),(byte[])otherSNMPObject.getValue()))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    
    
    
    /**
    *   Generates a hash value so SNMP Octet String subclasses can be used in Hashtables.
    */
    
    public int hashCode()
    {
        int hash = 0;
        
        // generate a hashcode from the embedded array
        for (int i = 0; i < data.length; i++)
        {
            hash += data[i];
            hash += (hash << 10);
            hash ^= (hash >> 6);
        }
        
        hash += (hash << 3);
        hash ^= (hash >> 11);
        hash += (hash << 15);
         
        return hash;
    }
    
    
    
    
    
    /** 
    *    Returns a String constructed from the raw bytes. If the bytes contain non-printable
    *    ASCII characters, tant pis! (Though it's fun when the bell rings!)
    */
    
    public String toString()
    {
        String returnString;
        
        /*
        if ((data.length == 4) || (data.length == 6))
        {
            returnString = new String();
        
            int convert = data[0];
            if (convert < 0)
                    convert += 256;
                returnString += convert;
                    
            for (int i = 1; i < data.length; i++)
            {
                convert = data[i];
                if (convert < 0)
                    convert += 256;
                returnString += "." + convert;
            }
        }
        else
            returnString = new String(data);
        */
        
        /*
        byte[] converted = new byte[data.length];
        
        for (int i = 0; i < data.length; i++)
        {
            if (data[i] == 0)
                converted[i] = 0x20;    // space character
            else
                converted[i] = data[i];
        }
        
        returnString = new String(converted);
        */
        
        returnString = new String(data);
        
        return returnString;
        
    }
    
    
    
    private String hexByte(byte b)
    {
        int pos = b;
        if (pos < 0)
            pos += 256;
        String returnString = new String();
        returnString += Integer.toHexString(pos/16);
        returnString += Integer.toHexString(pos%16);
        return returnString;
    }
    
    
    
    /** 
    *    Returns a space-separated hex string corresponding to the raw bytes.
    */
    
    public String toHexString()
    {
        StringBuffer returnStringBuffer = new StringBuffer();
        
        
        for (int i = 0; i < data.length; i++)
        {
            returnStringBuffer.append(hexByte(data[i]) + " ");
        }
        
        return returnStringBuffer.toString();
        
    }
    
    
    
}